Boeing 737 MAX family NEWS ONLY

Lecturing... Not much need to reply.
And as said, some crew would have taken the time to assess the problem.
 
Question for those more familiar with cabin aircon: if the outflow air is taken from under the floor, what's the flow route from cabin to underfloor?
 
The Spirit factory in Prestwick Scotland which does Airbus work, the part of the factory in Belfast which doesn't do Airbus work and the plant in Subang, Malaysia are apparently all still on the market looking for a new owner. Not acquiring the complete Ireland/Scotland operations might be why Airbus came down from their initial $1bn demand, I was surprised Airbus picked up the Morocco operation as well.
 
TomcatViP said:
Airliners are not instrumented like a laboratory gig. The gauges and procedures are indicative regarding the type of problem and more troubleshooting is expected to close on a faulty system. A technical investigation can´t stop at staring at the instrument panel. You know that. Mechanics do have often to trace back the faulty system and pilot´s indications are key to that.
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Yes, they are. And there has been nothing reported that would point a mechanic troubleshooting the pressurization system towards the plugs. I would more likely suspect the electrical connections at the Pressurization Controller before a crack or leaking door.

Look. The pressurization system on the older planes is pretty dumb. You tell it to maintain X pressure differential, it vents air out to hold the pressure there. It doesn't say, "Hey, wait, I'm needing a lot less outflow door that I should be using at this engine RPM, something isn't right." It's not like say, the Mass Airflow Sensor and ECU on a 2000s Chrysler Hemi, that says "I'm seeing a lot more air than I should be for how much throttle there is, something is wrong" and throws the engine into limp-home mode when Joe hotrodder hooked up a supercharger to his Hemi for Moah Powah!!!!

It might be possible to have such a system installed without modifying the airframe, as long as the motors that control the outflow valve are steppers and know where they are in their travel. Then you could simply reprogram the Pressurization Controller with a map comparing outflow position with commanded differential pressure versus engine RPM (and therefore how much bleed air you're packing into the tube).


TomcatViP said:
When those passengers reported thd problem, a significant piece of evidence was disregarded that should have been taken into consideration.
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Where were these passengers seated and can they describe to the cabin crew where they heard the sound? Can the cabin crew relay that information to the mechanics?




TomcatViP said:
That it would be by pedantism, inattention, fatigue, miscommunication, that very fact is there as surely as an uncompleted plane being put into service by Boeing.
IMOHO, the NTSB should have that covered in their investigation as well. It makes no sense otherwise.
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Have we seen a Final Report from the NTSB?
If not, how do you know that the NTSB isn't covering that?


TomcatViP said:
The plug blowing out at such a low alt would also indicate that an appropriate pre-flight inspection could have detected a faulty panel adjustment.
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Do me a favor.

Go try to see where the plug physically is on the aircraft, while you're standing on the ground 20 feet below it.

Now try to see if the plug is standing proud of the surface at any point. I'm willing to bet that the design actually has the skin of the plug sitting on top of the fuselage skin. That will make it stand 1-2mm proud of the skin around it, without a gap. It would also make it impossible to see light through any gap due to the shape of the fuselage.


TomcatViP said:
The faulty pressurization indicator in the climbing portion of the flight (at such a low alt, just above cabin pressure activation) could have seen another crew electing to turn back or circle the time the cabin crew made an inspection...

All this are signs that the craziness certainly didn´t stop at Spirit or Boeing.
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You are pointing at that cabin pressurization fault as if it's some smoking gun. IT IS NOT A SMOKING GUN. All it says is that the Controller cannot maintain ordered pressure differential. It could be that the primary controller itself is failing. There could be an electrical fault somewhere. In no way does it suggest that the cabin doors, baggage doors, or the door plugs might not be sealing properly.

The plane was literally on it's way to the Alaska Airlines maintenance depot at the end of this flight. What the hell more do you want to do?
 
DWG said:
Question for those more familiar with cabin aircon: if the outflow air is taken from under the floor, what's the flow route from cabin to underfloor?
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It follow the differential of pressure. Just replace P by V as in electricity (potential). Same principle.


@Scott Kenny :
- controllers are generally chosen to be fail-safe regarding the parameter they sample (at least statically - but you have a test function when there is any doubt). Repeatedly pointing at it when a cabin breach is signaled is like having a plumber ordering you to crank up the TV volume when you report hearing a leak. Is that really the kind of professionalism we want this industry to rely on?
- The available preliminary NTSB report is attached to one of my previous post. It does not mention in any way passengers alerting the crew on previous flights.
- Since you mention it in bold, CAPITAL and Underlined, Smoke is a very good way to detect any leak in a pressure vessel (remember fixing that inner tube that got punched somewhere when you were a teen?)


Last but not least, and regrettably, I see we can´t really have a conversation on that topic. Guessing most have better to do for the long w.e, and whishing you the best, let´s give it a break.
 
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One thing that I have not seen (or perhaps noticed) is whether the previous alarms were Repeats or just Recurs. Drives your criticality (urgency) and troubleshooting in different directions.
 
TomcatViP said:
It follow the differential of pressure. Just replace P by V as in electricity (potential). Same principle.


@Scott Kenny :
- controllers are generally chosen to be fail-safe regarding the parameter they sample (at least statically - but you have a test function when there is any doubt). Repeatedly pointing at it when a cabin breach is signaled is like having a plumber ordering you to crank up the TV volume when you report hearing a leak. Is that really the kind of professionalism we want this industry to rely on?
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That pressurization alarm has more than 5 different triggers.
Again, from the QRH posted on scribd, but differently presented:
"This indicates that the primary automatic cabin pressurization controller was disabled by a fault condition, which can be caused by
  1. a problem with the controller itself,
  2. one of the valves it controls,
  3. an excessive pressure differential,
  4. an excessive rate of cabin pressure change, or
  5. a high cabin altitude."
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Emphasis mine.

So when troubleshooting, you have multiple things to test. On the ground and in the air for each one.

Furthermore, the system does not say which of those 5+ possibilities caused the alarm. So you have to test all of them. Only one of the alarm triggers points towards the fuselage having a leak in it.

TomcatViP said:
- The available preliminary NTSB report is attached to one of my previous post. It does not mention in any way passengers alerting the crew on previous flights.
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Was the passengers reporting a weird noise mentioned before the NTSB started their prelim report?


TomcatViP said:
- Since you mention it in bold, CAPITAL and Underlined, Smoke is a very good way to detect any leak in a pressure vessel (remember fixing that inner tube that got punched somewhere when you were a teen?)
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The pressurization test procedures need to be followed as written, and I do not recall one ever authorizing smoke in the cabin as the test.
 
Scott Kenny said:
The pressurization test procedures need to be followed as written, and I do not recall one ever authorizing smoke in the cabin as the test.
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It would be an interesting experiment in social dynamics with fare-paying passengers on board. Probably fine on a charter flight for the Pyromaniac Society, other passengers might not approve.
 
TomcatViP said:
It follow the differential of pressure. Just replace P by V as in electricity (potential). Same principle.
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Yes, I'm quite aware that there will be a flow from high pressure to low pressure. What I want is the actual route taken. We know there's a flow from air-con pack to cabin through the air-con ducting, and from the underfloor area to the outflow valves, but what's the route out of the passenger cabin to the underfloor area. Floor vents? Through the galley? Whatever?
 
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Scott Kenny said:
The pressurization test procedures need to be followed as written, and I do not recall one ever authorizing smoke in the cabin as the test.
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Smoke to detect a leak in a bike tyre? Weird, use a bucket of water like everyone else.
 
Well, unless you are that Jamaican kid, you´ll use a water bucket like everyone else. That was implied :D

It´s just the principle that is the same (but smoke instead of bubbles).

But if you need an excuse to hose that pretty new cabin crew hostess...
 
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DWG said:
Yes, I'm quite aware that there will be a flow from high pressure to low pressure. What I want is the actual route taken. We know there's a flow from air-con pack to cabin through the air-con ducting, and from the underfloor area to the outflow valves, but what's the route out of the passenger cabin to the underfloor area. Floor vents? Through the galley? Whatever?
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IIRC, there's a floor level vent in the interior panels.

Air flows in through a big diffuser in the top of the cabin and through the eyeball vents above each seat.

(And I think you tagged the wrong dude about using smoke to find a leak in a bike tire.)
 
Scott Kenny said:
(And I think you tagged the wrong dude about using smoke to find a leak in a bike tire.)
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I started out commenting on using smoke in the cabin for pressurization testing, made the point about using a bucket along the way, then figured out everything else was probably wrong and deleted it, so was left with just the bucket of water - too lazy to move it to another post, and figured it was close enough people would realise the attribution.
 
aim9xray said:
Noted without comment. From the Daily Beast: How Boeing CEO’s Catastrophic Reign Could Become Criminal
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What often baffles me is how things have kinda came full circle, after Boeing was "tainted" by MDD, post 1997 takeover...

- 737 MAX death toll: 346 people - for criminally stupid corporate reasons

- DC-10 death toll, March 3, 1974: 346 people - for criminally stupid corporate reasons. https://en.wikipedia.org/wiki/Turkish_Airlines_Flight_981

I know it just a dumb coincidence, but it baffles me nonetheless...
 
DWG said:
That's what I thought, plenty of scope for whistling noises.
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you need a significant differential of pressure for that thing whistling. Think blowing in a saxophone.
Let me know, what do you think is the pressure in the cargo hold?

Also, have you heard anyone complaining about the vent valves in an airplane*? Airplane cabin are very noisy. That you hear the whistling of an airstream means its powerful. Abnormally powerful I should say...

*At least the non-organic ones
 
TomcatViP said:
you need a significant differential of pressure for that thing whistling. Think blowing in a saxophone.
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It doesn't take much, you just need airflow through, or across, an appropriate orifice. And it certainly doesn't take a deliberately designed orifice, my crutches will often whistle in the breeze.

As for pressure in the underfloor area, pretty much the same as in the above floor area, the issue is air circulation, not pressure differential. Air-con systems work on airflow due to fans, not due to pressure differentials, which in a small enclosed volume would soon equalise.
 
TomcatViP said:
you need a significant differential of pressure for that thing whistling. Think blowing in a saxophone.
Let me know, what do you think is the pressure in the cargo hold?
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Pressure in the cargo hold is the same as in the cabin.

The outflow valve is a door big enough for a human to crawl through and is located at the aft end of the after baggage compartment.
 
www.b737.org.uk

The Boeing 737 Pressurisation System

Technical website for Boeing 737 pilots and engineers. Site includes news, system and operating notes, technical photographs, databases and related links.
www.b737.org.uk www.b737.org.uk

With pictures of the outflow valve.

www.b737.org.uk

The Boeing 737 Air Conditioning System

Technical website for Boeing 737 pilots and engineers. Site includes news, system and operating notes, technical photographs, databases and related links.
www.b737.org.uk www.b737.org.uk

www.b737.org.uk

737-3/500 Air Conditioning System Schematic Diagram

737-3/500 Air Conditioning System Schematic Diagram
www.b737.org.uk www.b737.org.uk

For 737-300/500, with link to equivalent for -400. Unfortunately I can't spot the link to the outflow valve on either of these.
 
www.theguardian.com

‘We’re in limbo’: Boeing takeover leaves longtime Belfast factory under threat

Workers and politicians fear steep job cuts at Northern Ireland’s Spirit AeroSystems, which has about 3,500 workers
www.theguardian.com www.theguardian.com

(Not directly 737 relevant, but part of the Spirit acquisition that is)

TLDR: The Belfast site's workload is 40% Airbus, 60% RR, Bombardier, Honda, the workforce is worried about whether the 60% will stay.

I hadn't realised it was still at the old Shorts & Harland site (the article calls it Short Bros, but Belfast was a joint venture if memory serves). Interesting for me as I spent my career at what was Short Bros HQ at Rochester Airfield (later Elliots, GEC/Marconi and finally BAE Systems).
 
Heard some rumblings, Airbus has essentially taken on the unprofitable parts of Spirit with compensation in the hope that makes the rump of Spirit more attractive. The Malaysian, Scotland and part of the Belfast plant are still on the market with the hope they can be spun off into an independent company but the rumour is Airbus has a buyer of last resort deal, if Boeing cant find a buyer (like a private equity firm) then Airbus has agreed to purchase them.
 
DWG said:
For 737-300/500, with link to equivalent for -400. Unfortunately I can't spot the link to the outflow valve on either of these.
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I appreciate your effort to present the information about the 737's air conditioning and pressurisation systems. It should help focus attention on what I think is the problem that lies at the root of what caused the lapse of control in Boeing, and the death of 346 people in two 737 Max crashes.

To wit: a perverse leadership culture so focused on making money that it lost sight of the consequences of shoddy aircraft manufacturing - 346 dead, which would have been even more if the Alaska Air had lost its plug in slightly different circumstances.

The fact that the entire run-up to the Alaska Air incident happened AFTER Boeing's leadership promised better practices following the two Max crashes tells me that this leadership is incompetent, and should have stepped down years ago.
 
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Arjen said:
To wit: a perverse leadership culture so focused on making money that it lost sight of the consequences of shoddy aircraft manufacturing - 346 dead, which would have been even more if the Alaska Air had lost its plug in slightly different circumstances.

The fact that the entire run-up to the Alaska Air incident happened AFTER Boeing's leadership promised better practices following the two Max crashes tells me that this leadership is incompetent, and should have stepped down years ago.
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Worse, it is evident that many executives bonuses were attached to "airplane leaving factory" not "airplane delivered to customer." Because there were planes leaving the factory with safety of flight work incomplete (and people not knowing that, which is a different issue).
 
Boeing pleads guilty to criminal guilt charge.
www.bbc.com

Boeing to plead guilty to criminal fraud charge over 737 Max crashes

Families of the people who died on the flights five years ago have criticised it as a "sweetheart deal".
www.bbc.com www.bbc.com
Boeing has agreed to plead guilty to a criminal fraud conspiracy charge after the US found the company violated a deal meant to reform it after two fatal crashes by its 737 Max planes that killed 346 passengers and crew.

The Department of Justice (DoJ) said the plane-maker had also agreed to pay a criminal fine of $243.6m (£190m).
[...]
The company has been in crisis over its safety record since two near-identical crashes involving 737 Max aircraft in 2018 and 2019. It led to the global grounding of the plane for more than a year.

In 2021, prosecutors charged Boeing with one count of conspiracy to defraud regulators, alleging it had deceived the Federal Aviation Administration (FAA) about its MCAS flight control system, which was implicated in both crashes.

It agreed not to prosecute Boeing if the company paid a penalty and successfully completed a three-year period of increased monitoring and reporting.
[...]
In May, the DoJ said it had found Boeing had violated the terms of the agreement, opening up the possibility of prosecution.

Boeing's decision to plead guilty is still a significant black mark for the firm because it means that the company - which is a prominent military contractor for the US government - now has a criminal record.
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The problem with activating the deferred prosecution and allowing Boeing to plead guilty is DoJ no longer has it hanging over Boeing's head like the sword of Damocles, concentrating the minds of the Boeing Board. It might have been a more effective punishment to extend the deferred prosecution for another three years.
 
The Economist. Paywalled, but here are some excerpts.

www.economist.com

Once high-flying Boeing is now a corporate criminal

Its woes illustrate the excesses of a lean-and-mean era in corporate America
www.economist.com www.economist.com

First, its acquisition of McDonnell Douglas in 1997 was part of what The Economist then approvingly called “one of the great industrial upheavals of all time”: the hammering together of America’s fragmented defence industry into a few global Goliaths. Since then consolidation has been the name of the game across corporate America. The second trend was outsourcing. In 2005 Boeing joined the rush to offload capital-intensive manufacturing and cut labour costs by selling off parts of its production line, becoming an assembler of planes rather than a vertically integrated manufacturer. Third, like many listed American firms, Boeing showered stockholders with cash via share repurchases and dividends rather than investing in non-financial innovation.

All three trends delighted Wall Street.

[...]

As the Wall Street Journal reported, that divestment decision was part of a trend to develop “asset-light” firms focused on intellectual property; most memorably, Boeing outsourced most of the manufacturing of the Dreamliner. Yet distributing production brought its own headaches. Delays, cost overruns and supply-chain snags became vividly apparent during the covid-19 pandemic. On July 1st Boeing said it would reacquire Spirit for $8.3bn, putting restoring safety as the top priority. The pendulum has swung back to vertical integration.

[...]

The megamerger trend, too, has had chequered results. Buying McDonnell Douglas’s armsmaking prowess vaulted Boeing into the top-tier of defence contractors. The logic appeared sound. Military budgets tend to be reliable counterweights to the vagaries of the civil-aviation market, making earnings more predictable. Government-backed innovations in military technology can also benefit commercial aircraft. Yet too long at the top table appears to have made Boeing’s defence and space businesses fat and lazy.

[...]

being lean and mean is all well and good, but being too much so can come at a grave cost to everyone involved.
 
Long story short--Mamas, don't let Mitt Romneys build airplanes.

"At Boeing, our favorite movie is Glengarry, Glen Ross."

"One aircraft is moving east at 500 knots--another is flying west at 450 knots. So, how many lay-offs does it take to have them both crash?"

Show your work
 
publiusr said:
Long story short--Mamas, don't let Mitt Romneys build airplanes.

"At Boeing, our favorite movie is Glengarry, Glen Ross."

"One aircraft is moving east at 500 knots--another is flying west at 450 knots. So, how many lay-offs does it take to have them both crash?"

Show your work
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“First prize is a Cadillac El Dorado. Second prize is steak knives. Third prize is a crater in a cornfield and a five year NTSB investigation.”
 
Was a good month for 777F orders if abysmal for passenger aircraft with only 3 and one of those is a replacement for the Alaska aircraft that lost the door plug (Boeing are taking back the Alaska aircraft and haven't indicated whether it will be repaired or scrapped).
 
WatcherZero said:
(Boeing are taking back the Alaska aircraft and haven't indicated whether it will be repaired or scrapped).
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Interesting. I can see why Alaska, or (almost) anyone else, wouldn't want it on their books from a PR viewpoint, but are the engineering risk factors for the airframe the decompression damage, or that there might be further unlogged work?

If you give him a good enough discount I'm sure Michael O'Leary will be perfectly willing to take it for Ryanair.
 
DWG said:
Interesting. I can see why Alaska, or (almost) anyone else, wouldn't want it on their books from a PR viewpoint, but are the engineering risk factors for the airframe the decompression damage, or that there might be further unlogged work?
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At the very least, you'd have to replace all the locking hardware around that door plug. I wouldn't trust ANY of it after the blowout.

It's also self-evident that there was unlogged work on that airframe, so I wouldn't trust it farther than I could throw the airframe.
 
Boeing has apparently written to airline customers expecting MAX deliveries in 2025 and 2026 and told them to expect fresh delays of between 3 and 6 months on their delivery.
 
That's entirely predictable if Boeing was planning deliveries on the basis of a hike in production rates. OTOH I'm surprised it's only 3 to 6 months.
 
www.flightglobal.com

Southwest 737 hammered by high ground winds before ‘Dutch roll’ incident: NTSB

Southwest has since inspected its entire 737 Max fleet and Boeing has reminded airlines about "high-wind" inspections.
www.flightglobal.com www.flightglobal.com

There's enough details here to see why Boeing would claim the issue was unique to the aircraft, and why NTSB would differ with them.

TLDR: The aircraft had been flying around with damaged tail controls, probably since it was exposed to high winds (gusts to 73mph) on the ground at New Orleans on 16-17 May. While the problem only became a major one with the dutch roll incident on the 25th, the captain of that flight had noticed a log entry for yaw damper issues, resolved by "resetting a few stall management yaw damper computer codes” - whatever that means, I genuinely can't tell. The NTSB notes that anomalies started showing up on the first flight after Southwestern did some scheduled maintenance checks on the standby tail PCU on the 23rd.

So yes, there were possibly aircraft unique issues, as Boeing claimed. But those issues may have been masked by the tail controls until something related to the checks on the 23rd, in which case there's definitely whole fleet issues to be investigated to understand how the controls were masking the damage, and how the maintenance check changed that. And also potential whole fleet issues related to the gust-damping system intended to stop the rudder being slammed against its stops. (Plus did someone in Southwestern maintenance simply reset a breaker rather than properly investigating the yaw damper anomalies).

So overall, yes, NTSB were right to be pissed-off with Boeing over and above violating investigation protocols. And yes, Boeing's Chief Engineer should have known there was more involved and not tried to dupe the press.
 

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